It is known to provide seals between a rotatable shaft and an opening through which the shaft passes in order to keep a lubricant such as oil or grease on one side of the seal and to prevent the lubricant from leaking to the other side of the seal.
In many applications, the dimensions and alignment of the shaft and the opening are relatively accurate, and, in such cases, sealing between the shaft and the housing opening can be implemented with a conventional oil seal. There are two common types of conventional oil seals: 1) a radial lip shaft seal, which has a fluorine rubber lip that is held in sealed contact against a shaft using a spring, and 2) a polytetrafluoroethylene (PTFE) seal, which comprises a PTFE lip held against the shaft by a flexible portion of the seal body. However, conventional seals can only tolerate a certain amount of shaft-to-opening misalignment, both when the shaft is stationary and when it is rotating, without allowing lubricant to escape through the seal.
In some applications, the amount of shaft-to-opening misalignment is greater than what can be tolerated by conventional shaft seals. It would therefore be desirable to provide an improved seal assembly that can tolerate relatively large misalignments and/or deviations between a rotatable shaft and an opening in a housing.